Preparation of substituted alkyloltetrahydropyran



Patented Jan. 10, 1950 REISS'UED JUL18 1950 PREPARATION OF SUBSTITUTED ALKYLOLTETRAHYDROPYBAN William F. Gresham and William E. Grigsby, Wilmington, Del., assignors to E. I. du Pont do Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application October 24, 1047, Serial No. 782,030

9 Claims. (Cl. 260-333) This invention relates to a process for preparation of tetrahydropyrans, and more particularly to the preparation of alkylol substituted tetrahydropyrans from an aldehyde and a 1,3-diene.

One object of the invention is to provide a process for the preparation of new compositions of matter. Another object is to provide a process for the preparation of alkylol substituted hydroxy tetrahydropyrans by the interaction of an aidehyde with a 1,3-diene and especially butadiene. Still another object is to provide a process for the preparation of alkylol substituted hydroxy tetrahydropyrans by the reaction of formaldehyde with butadiene. Yet another object is to provide conditions for effecting the reaction while at one and the same time inhibiting the polymerization of the'butadiene. Other objects and advantages of the invention will hereinafter appear.

The above and other objects are accomplished by reacting an aldehyde such as formaldehyde with a 1,3-diene such as butadiene in the presence of an acid condensation catalyst and a polymerization inhibitor. formal substituted tetrahydropyrans are obtained from formaldehyde and butadienes.

(1) 3-hydroxy-4-methyloltetrahydropyran and (2) its formal:

CHCHiOH CH CHOH CH CH;

These alkylol and products including 4-vinyl dioxane-l,3.

(3) 4-hydroxy-3-methyloltetrahydropyran and (4) its formal:

OH OH CH CH CHOH CH CH,

having a boiling point of 142 C. Inasmuch as this intermediate can be reconverted to the desired product, it can be recycled and by this means the desired product produced in the substantial absence of these intermediates.

Examples are given describing the preferred embodiments of the invention in which parts are by weight unless otherwise stated.

Example 1.A charge of 134.4 grams H2O, 3.8 grams H1804, 0.2 gram hydroquinone, 40.8 grams paraformaldehyde and 24 grams butadiene was processed in a 325 m1. silver-lined shaker tube at 121-13574 hrs., during which time the autogenous pressure fell from 250-20 p. s. i. The discharge (200.4 grams, light brown liquid) contained 17.5% of the charged CI-IzO, of which amount 71% was recovered in the distillate. The discharge was carefully neutralized with NaOH and distilled. The first cut (85-l00, 182.4 grams) contained an upper layer of 6 cc. of intermediate The next cut was the formal of 3-hydroxy-4-methyloltetrahydropyran, 18.6 grams. This substance boils at 79/10 mm. or 56/2 arm, has a refractive index (as a supercooled liquid) of 1.4668 at 25 C.

It is a crystalline, water-soluble solid, melting 46 at 55 (ex ether or cyclohexane) The remainder.

18.6 g., boiled at 98-124" C. at 1 mm. pressure. Redistillation of this fraction gave a pure compound boiling at 120 C./1 mm. This glycol is a viscous, water-soluble, nearly colorless oil with a refractive index of 1.4863 at 25. The residue 5 pound).

was 9.7 g. or 3.7 g. net (allowing for NazSOs).

Example 6..A mixture comprising 202.5 s.

841m: Formal oi Wafer lnsol Enemy! 3-Hydroxyuble Layer mm 4-rnethylol- Considered Total pm tetrabydroas A3 pyran Dihydropyran Per cent Per mu Per cent Per cent 0 on 0.5.) 31.1 29.1 10.1 76.0 Yield onconsumedOHgO) 23-4 86-4 6.7 71.6

Example 2.The aqueous fraction from Example 1, including the upper layer, was recycled with make-up CHaO, H2804, hydroquinone, and butadiene under the same conditions (121-125/4 lira/320459 p. s. i.). Unconverted formaldehyde 320, 8.8 g. conc. HCl, 0.3 g. hydroquinone, 82.1 g. paraformaldehyde, and 27 g. butadiene was processed at 123-13073 hrs/410450 p. s. i. (autogenous pressure). The product was analyzed as described in Example 1.

Formal of Water Insol- Zgm x 3-Hydrcxyuble Layer mmhym 4-methylol- Considered Total tetrshydross pm pyran Dih Per cent Per cent Per cent Per cent Oonv. 011043;) 25.1 42.5 7.2 74.8 Yield on consumed OHsO) 17.3 43.8 2.5 63.6

amounted to 25.6%. The product was analyzed as described in Example 1. The upper layer of the aqueous distillate was 16 cc. (an increase of Example 7.-A mixture consisting of 116.6 8. acetic acid, 3.5 g. H3504, 0.2 g. hydroquinone, 24 g. butadiene, 42.0 8. paraformaldehyde. 26.2 g.

10 cc. over the charged amount). so H2O was processed at 118-125/4 hrs. Titration Formal of Water Insolz'ggmfl 3-Hydroxyuble Layer am +methyio1- Considered Total i tetrahydroas A-3- p pynm Dihydropyl'ln Percent Permit .Percent Percent 0011mm on O4Hs) Zi- 0 86. 3 N. 8 86.1 Yield on consumed OHsO) 31.3 50. 3 12. 4 84. 0

Example 3.The aqueous distillate containing 16 cc. of upper layer obtained in Example 2 was processed with make-up formaldehyde (12.7 g.) and 4.4 g. of H2804 in the absence of butadiene at 160-163 C. for 1 hour. Distillation of the product, after neutralization of the H2804 with aqueous caustic, gave 6.8 g. of the formal of was unconverted.

of the discharge showed that 7% of the CHaO Enough NaOH was added (3 g.) to neutralize the H2804, and the water and acetic acid were removed by distillation. The first cut was 28.1 g. of the solid formal o'f'8- hydroxy 4 methyloltetrahydropyran. The second cut, 5.3 g., boiled from 61/1.5 mm. to 96.5/1.5 mm., while the next fraction, 4.9 g.. had a boiling range of 98.5-101/1.5 mm., and a refractive index (25) of 1.4618. The final cut, B. P. 107-140/1.5 mm. weighed 10.5 g. The net residue was 3 g. The formal was produced in 44% conversion (based on C4H0) and 47.3% yield (based on CH4O consumed). The higher boiling fractions are esters and are assumed to contain the monoand (ii-acetates of 3 hydroxy 4 methyloltetrahydropyran.

This example illustrates, inter alia, that when an organic acid such as acetic acid is used as a diluent in place of water, esters are obtained water and 10.8 g. of H2804 for 7.5 hours. Neutral- 7 as well as the cyclic formal. Upon analysis the emes properties of the products were found to be as follows:

examples of which are wrosallol, catechol, t-butyl cateehol, etc.

Properties Found Oslo.

1 a-liydmsy-l-methyloltetrahydropyran (or an mer odorless, colorless oil 200-201' Om mm.... P ap mm up! 1.4867 Solubility W111i}; organic solvan DVlscosity at 100' I 5115 oentistokes I- Molecular refraction. 32 40 Per cent 54. 6 Per cent 9.08 H xyl number 860 A scent hydroxyl lgroulps, m. e .[2 g. 0 0 2 Formal oi 3-hydroxy-4-met ylo tetrahy opyran (or an isomer):

Oolorlem, almos odorless solid- Boilin point 79ll0 mm Solubility wHrO, ethanol, methanol, acetone. Melting int Recrysta ration solvents Ether oyelohexnne no" (su rcooled liquid). 1.4008. Molec or weight 141 144 Iodine number 0 0 Haidlroxyl number- 0 0 3 4- figs-dioram Oolor mobile liqui Odor, ethereal- Boiling point- 142.19. 301 bility 121'}: 0/25 Insoi l1 g I K100: organio so vents.

Generally speaking, the More-illustrated reactions may be conducted at temperatures between 100 and 200 C. with an optimum range between 120 and 130 C. A higher temperature tends to give greater tar formation and wider by-product distribution. The reaction is conducted at these temperatures for processing times ranging from 15 minutes (at 150 C.) to 6 hours (at 120 (1.); a four hour reaction time gave purer 3-hydroxy-4-methyloltetrahydropyran.

The ratio of formaldehyde to butadiene may range from 1 to 6 moles of formaldehyde per mole of butadiene, although the optimum is 3 or more moles formaldehyde per mole of the butadiene. The formaldehyde concentrations should range between 10 and 40% of the total charge with optimum concentrations between and Other aldehydes may be used such as acetaldehyde, propanal, the butanals, and the higher straight and branched chain aldehydes. These aldehydes, as well as formaldehyde may be reacted, (in accord with the invention with the proportions and operational procedures used for the formaldehyde-butadiene reaction) with 1,3- dienes other than butadiene such as, 2-methyi 1,3-butadiene, Z-ethyl 1,3-butadiene and thelike.

Any suitable acid condensation catalyst may be employed such, for example, as hydrochloric acid, phosphoric acid, boron trifluoride (either alone or as a complex with water or aldehyde), aromatic sulfonic acids, or other strongly acid condensation catalysts. The catalysts should be employed in concentrations equivalent to the concentration of sulfuric acid when it is used, i.e., concentrations between 0.5 and 8% of the total charge, and optlmum ratios from 1.25 to 2% of sulfuric acid.

Any suitable form of formaldehyde may be used such, for example, as 37% aqueous formaldehyde known commercially as Formalin) paraformaldehyde, or trioxane. Polymerization inhibitors others than hydroquinone may, likewise, be used.

Because the material boiling higher than the formal, oi 8-hydroxy-4-methyloltetrahydropyran contains primarily a compound boiling at 120 C./ 1 mm., and because from theoretical considerations, isomers should be formed. this fraction is considered to be 3-hydroxy-4-methyloltetrahydropyran in the calculation of yield data. These calculations are, it appears, wholly justifled since materials boiling lower and higher than 120 C./ 1 mm., by processing with aqueous sulfuric acid. (See Example 5.)

The compounds prepared are valuable intermediates for use in the preparation of plasticizers and other compounds.

The product of the examples of 3-hydroiw-4- methyloltetrahydropyran and/or 4-hydroxy-8- methyloltetrahydropyran and/or stereoisomers thereof and in the claims will be referred to as 3-hydroxy-4-methyioltetrahvdropyran.

We claim:

1. In a process for the preparation of alkylolsubstituted hydroxytetrahydropyrans, their cyclic formals and 4-vlnyl-1, 3-dioxane which comprises reacting at least one mol of formaldehyde per mol of butadiene in the presence of a polymerization inhibitor and an acidic condensation catalyst at a temperature between and 200 C. and under autogenous pressure.

2. The process of claim I conducted with a ratio of from 1 to 6 moles of formaldehyde per mole of butadiene.

3. The process of claim 1 in which from 10 to 40% of formaldehyde is used based on the total charge.

4. A process for the preparation of 3-hydroxy- 4-methyloltetrahydropyran which comprises reacting from one to six mols oi formaldehyde per mol of butadiene in the presence of water, a polymerization inhibitor and an acidic condensation catalyst at a temperature between 100 and 200 C., neutralizing the catalyst and recovering the 3-hydroxy-4-methyloltetrahydropyran after diswas . 7 tillina 08 the formal of 3-hydroxy-4-methgl0ltetrahydropyran.

5. process for the preparation of the formal of 3-hydroxy-4-methyloltetrahydropyran which comprises reacting from one to six mols of formaldehyde per mol of butadiene in the presence of water, a polymerization inhibitor and an acidic condensation catalyst at a temperature between 100 and 200 0., neutralizinz the catalyst aml recovering the formal of 3-hydroxy-4-methylottetrahydropyran bydistillation.

6. A process for the preparation of l-vinyl-l,

S-dioxane which comprises reacting from 1 to 6 mols of formaldehyde per mol of butadiene in the presence of a polymerization inhibitor and in condensation catalyst at a temperature between 100 and 200 0., neutralizing the catalyst and separating from a distillation out between 85' and 100 C. the 4-viny1-L3-dl0xane.

I. i-vinyl-lj-dioxane. v

8. An alkylol substituted tetrahydropyran, mduced by reacting formaldehyde with butadieiie in the presence of water, a polymerization inhibitor and an acidic condensation catalyst at a 10 mm., and a refractive index of 1.4668 at 25 C.

WILLIAM F.- GRESHAM. WILLIAM E. GRIGSBY.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS lumber Name mte 1,302,391 Bitter Nov. '2. 1944 2,421,882 Arundale June 10, 1947 

1. IN A PROCESS FOR THE PREPARATION OF ALKYLOLSUBSTITUTED HYDROXYTETRAHYDROPYRANS, THEIR CYCLIC FORMALS AND 4-VINYL-1,3-DIOXANE WHICH COMPRISES REACTING AT LEAST ONE MOL OF FORMALDEHYDE PER MOL OF BUTADIENE IN THE PRESENCE OF A POLYMERIZATION INHIBITOR AND AN ACIDIC CONDENSATION CATALYST AT A TEMPERATURE BETWEEN 100 AND 200*C. AND UNDER AUTOGENOUS PRESSURE.
 7. 4-VINYL-1,3-DIOXANE. 